JP5041706B2 - Sulfuric acid resistant structure and sulfuric acid resistant repair material - Google Patents

Description

The present invention relates to a sulfate-resistant structure composed of a mortar composition containing a binder, a fine aggregate, and water , and a sulfate-resistant repair material .

  Various types of coal ash such as fly ash and clinker ash are discharged from coal-fired power plants. Fly ash is widely used as a concrete admixture in dams and road pavements to improve the long-term strength of concrete or reduce drying shrinkage. In addition, clinker ash is used as a roadbed for a permeable sidewalk or as a rainwater storage material because it has a high water retention capacity and is hard to crush.

However, not all by-products of coal-fired power plants are being used effectively. Among them, ash (referred to as “PFBC ash”) remaining after burning coal and limestone in a pressurized fluidized bed (called “PFBC ash”) has a lower SiO ₂ content than that of fly ash. and since the content of sO ₂ is often not satisfy the JIS standard fly ash, not effectively utilized as fly ash.

  As an example of the use of PFBC ash, as described in the following document, PFBC ash is mixed with cement as an alternative material or admixture for cement and fine aggregate contained in general concrete compositions. It is known to do.

  Patent Document 1 proposes a concrete composition having a practically sufficient compressive strength in which approximately 60% by weight of cement is replaced with PFBC ash.

  Patent Document 2 proposes an admixture made of PFBC ash. That is, as an admixture in a concrete composition, coal ash collected from a dust collection facility after coal for desulfurization is combusted together with limestone powder in a pressurized fluidized bed. It has also been shown that the strength of concrete can be improved by about 10% to 30% by using this admixture at a rate of replacing 15% to 30% by weight of the cement component of concrete.

Japanese Patent Laid-Open No. 11-147747 Japanese Patent Laid-Open No. 11-012000

  However, in the inventions of Patent Documents 1 and 2 described above, in a concrete composition containing cement, a part of the cement is replaced with PFBC ash. That is, in the known technology, it is essential to contain cement as a binder for the concrete composition, and even if PFBC ash is used, it is the same as a conventional general (not using PFBC ash) concrete composition. PFBC ash is only used as a substitute for part of the cement because it is required to have a certain degree of strength or higher, and naturally it is not a substitute for the whole cement and it can Neither was considered. Therefore, in the conventional concrete composition, the amount of PFBC ash used is limited.

  The present inventor has paid attention to a mortar composition using cement from the viewpoint that it is desirable to use PFBC ash more effectively as a substitute material for the entire cement in order to use PFBC ash more effectively. Because the mortar composition does not need to have the same strength as the concrete composition depending on its use, even if the mortar cement is entirely replaced with PFBC ash, a mortar composition having a strength satisfying the JIS standard can be obtained. Conceivable.

In view of the above, an object of the present invention is to provide a sulfate-resistant structure and a sulfate-resistant repair material composed of a practical mortar composition using PFBC ash.

The present invention relates to a sulfate-resistant structure used in an environment where it comes into contact with sulfuric acid , and includes a binder containing PFBC ash and blast furnace slag fine powder , a fine aggregate, and mortar containing no cement. It is characterized by comprising a composition.

In the mortar composition constituting the sulfate-resistant structure of the present invention, the ratio of the binder to water (hereinafter referred to as “binder water ratio”) is 1.7 to 2.3, and the ratio of the binder to fine aggregate (hereinafter referred to as “bond”). The “fine aggregate ratio”) is preferably about 3.0. However, these ratios can be appropriately increased or decreased depending on the type of the binder or fine aggregate.

In the sulfuric acid resistant structure of the present invention , the mortar composition has a compressive strength of 18 N / mm2 or more at a material age of 28 days, and a bending strength of about 1/5 to 1/7 or more of the compressive strength. Features.

Furthermore, the sulfate-resistant structure of the present invention is characterized in that the PFBC ash acts as an alkali stimulating agent, thereby developing latent hydraulic properties and having a dense hardened body structure.
The present invention also relates to a sulfate-resistant repair material applied to a sulfate-resistant structure that is used in an environment that is in contact with sulfuric acid, the binder comprising fine PFBC ash and blast furnace slag fine powder , fine bone A mortar composition containing a material and water and not containing cement is characterized.

Since the sulfate-resistant structure and the sulfate-resistant repair material of the present invention do not use cement as a binder, and replace all the conventional cement with PFBC ash and blast furnace slag fine powder , use of PFBC ash The effective use is greatly improved. Moreover, since PFBC ash which is a waste is used instead of cement, an inexpensive sulfuric acid resistant structure and a sulfuric acid resistant repair material can be provided.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated concretely, this invention is not limited to these Examples.

The following examples have a sulfuric acid and excellent sufficient strength as a mortar composition, mortar composition, resistance of the present invention used in an environment in contact with the sulfuric acid, such as sewage-related facilities and spas It shows that it can be used as a material for sulfuric acid structures and sulfuric acid resistance repair .

  The examples are mortar compositions prepared using PFBC ash and blast furnace slag fine powder as the binder and mixed sand as the fine aggregate, and the compressive strength and bending strength thereof were measured. Mixed sand is a mixture of sea sand and mountain sand in a ratio of 1: 1.

  Further, as a comparative example, the strength was similarly measured for a mortar composition prepared using ordinary Portland cement (hereinafter referred to as “ordinary cement”) instead of PFBC ash.

  First, Table 1 shows specific surface areas, densities, and water absorption rates of the binders and fine aggregates used in Examples and Comparative Examples, respectively.

次に、実施例、比較例において使用された結合材（ＰＦＢＣ灰、普通セメント、高炉スラグ）及び細骨材（混合砂、高炉スラグ水砕砂）の化学組成を、表２に示す。

Next, Table 2 shows the chemical composition of the binder (PFBC ash, ordinary cement, blast furnace slag) and fine aggregate (mixed sand, blast furnace slag granulated sand) used in Examples and Comparative Examples.

更に、実施例、比較例のモルタル組成物の示方配合量を、表３に示す。示方配合とは、所定の品質のコンクリートが得られるような配合で、仕様書又は責任技術者によって指示される配合のことである。

Further, Table 3 shows the blending amounts of the mortar compositions of Examples and Comparative Examples. Indication blending is a blending that gives concrete of a predetermined quality, and that is specified by a specification or a responsible engineer.

表３において、「１７１００」のように５桁の供試体番号を有する供試体は、結合材としてＰＦＢＣ灰と高炉スラグ微粉末を使用した供試体であり、上２桁は結合材水比を、下３桁はＰＦＢＣ灰高炉スラグ微粉末比を示す。また、「ＲＥ１７」のように４桁の供試体番号を有する供試体は、結合材として普通セメントと高炉スラグ微粉末を使用した供試体であり、下２桁は結合材水比を示す。

In Table 3, a specimen having a 5-digit specimen number such as “17100” is a specimen using PFBC ash and blast furnace slag fine powder as a binder, and the upper two digits are the binder water ratio. The last three digits indicate the PFBC ash blast furnace slag fine powder ratio. A specimen having a 4-digit specimen number such as “RE17” is a specimen using ordinary cement and blast furnace slag fine powder as a binder, and the lower two digits indicate a binder water ratio.

  Prepared with the formulation shown in Table 3 and cured to prepare a mortar composition. As curing conditions, underwater standard curing was performed at 20 ° C until the specified number of days (7, 28, 91 days). About the obtained mortar composition, compressive strength and bending strength were measured based on JIS R5201.

  About the mortar composition of said Example and a comparative example, the result of a compressive strength test is shown in Table 4, and the result of a bending strength test is shown in Table 5.

表４から、ＰＦＢＣ灰が使用された供試体はいずれも、普通セメントが使用された供試体と比較して強度が 55 % 〜 60 % 程度劣っているものの、材齢 28 日で 18 N/mm² 前後となり、JIS A 5308（材齢 28 日における予備強度が18 N/mm² 以上）を満たすことがわかる。また、表５から、ＰＦＢＣ灰が使用された供試体はいずれも、普通セメントが使用された供試体と比較して強度が 35 % 〜50 % 程度劣っているものの、材齢 28 日で 5 N/mm² 前後となり、下記の文献１）及び２）に記載されている曲げ強度の条件（圧縮強度の 1/5 〜 1/7 程度以上）を満たすことがわかる。

From Table 4, all specimens using PFBC ash were 18 N / mm at 28 days of age, although the strength was about 55% to 60% inferior to those using ordinary cement. ^{It is about 2} and it can be seen that JIS A 5308 (preliminary strength at the age of 28 days is 18 N / mm ² or more) is satisfied. Also, from Table 5, all the specimens using PFBC ash were 5 N at the age of 28 days, although the strength was 35% to 50% inferior to the specimens using ordinary cement. / mm ² becomes longitudinal, or 1/5 - 1/7 of the condition (compressive strength bending strength are described in the literature 1) and 2) below) it can be seen that satisfy.

1) Co-authored by Takemura Kazuo et al .: Construction Materials, Morikita Publishing, p.88, 1998
2) Eiichi Tazawa: Ace Concrete Engineering, Asakura Shoten, p.81, 2004
Therefore, it can be seen that the mortar composition in which PFBC ash is used has sufficient strength for practical use, and PFBC ash can be used as an alternative material for ordinary cement depending on the application.

  Next, the relationship between the binder water ratio and strength of the mortar composition in which PFBC ash is used will be described. FIG. 1 is a diagram showing the relationship between the binder water ratio and the compressive strength of the mortar compositions of the examples. FIG. 2 is a graph showing the relationship between the binder water ratio and the bending strength of the mortar compositions of the examples. In order to make the conditions uniform, data of a specimen having a ratio of PFBC ash to blast furnace slag fine powder (hereinafter referred to as “PFBC ash / blast furnace slag fine powder ratio”) of 1.0 is plotted.

  From FIG. 1 and FIG. 2, in the specimens using PFBC ash, a linear relationship is established between the compressive strength and the binder water ratio, and the bending strength and the binder water ratio. It can be seen that as the amount of PFBC ash used increases, the compressive strength and bending strength improve.

  From the above, the mortar composition in which PFBC ash is used has a practically sufficient strength, and PFBC ash can be used as an alternative material for ordinary cement depending on the application, and the PFBC ash used in the mortar composition can be used. It can be seen that as the amount increases, the compressive strength and bending strength improve.

  Next, while using PFBC ash and fine powder of blast furnace slag as a binder, a mortar composition using mixed sand or ground granulated blast furnace slag instead of fine aggregate is prepared, and its sulfuric acid resistance is improved. It was measured. Moreover, it measured also about the mortar composition produced using the normal cement instead of PFBC ash as a comparative example. In addition, the raw material used for the mortar composition of an Example is the same as the raw material used by the said strength test.

  Table 6 shows the blending amounts of the mortar compositions of this example and the comparative example. The difference from Table 3 is that a row of blast furnace slag granulated sand is added and the value of the indicated blending amount.

表６で、「ｎ２００５０」のように６桁の供試体番号を有する供試体は、結合材としてＰＦＢＣ灰と高炉スラグ微粉末とが使用された供試体であり、「ＮＣｎ」のように３桁の供試体番号を有する供試体は、結合材として普通セメントが使用された供試体であることを示す。また、「ｎ」、「ｂ」は、細骨材としてそれぞれ混合砂、高炉スラグ水砕砂が使用されたことを示す。

In Table 6, a specimen having a 6-digit specimen number such as “n20050” is a specimen in which PFBC ash and fine powder of blast furnace slag are used as a binder, and 3 digits such as “NCn”. The specimens having the specimen number of ## EQU1 ## indicate that specimens in which ordinary cement is used as the binder. “N” and “b” indicate that mixed sand and blast furnace slag granulated sand were used as fine aggregates, respectively.

It was prepared with the formulation shown in Table 6, molded to 4 × 4 × 4 cm ³ and cured to prepare a mortar composition. The curing conditions were standard underwater curing at 20 ° C up to 21 days of age. The obtained mortar composition was immersed in a 10% sulfuric acid solution, and the mass was measured every predetermined number of days (0, 1, 2, 4, 8, 16, 32 days).

  FIG. 3 shows the sulfuric acid resistance test results of the mortar compositions of Examples and Comparative Examples using mixed sand as fine aggregates, and FIG. 4 shows the mortar compositions of Examples and Comparative Examples using blast furnace slag granulated sand. It is a figure which shows the sulfuric acid resistance test result of a thing.

  From Fig. 3, the specimens using PFBC ash (n20050, n20100, n20125) have a mass reduction rate of about 20% smaller than that of specimens using ordinary cement (NCn) and have high sulfuric acid resistance. I understand. It can also be seen that the greater the amount of PFBC ash used, the smaller the mass reduction rate and the higher the sulfuric acid resistance.

  In addition, from FIG. 4, the specimens using PFBC ash (b20050, b20100, b20125) have a mass reduction rate of about 10% smaller than that of specimens using ordinary cement (NCb), and are resistant to sulfuric acid. I understand that it is expensive. It can also be seen that the greater the amount of PFBC ash used, the greater the mass reduction rate and the lower the sulfuric acid resistance.

  Finally, the relationship between the mass reduction rate of the aforementioned sulfuric acid resistance test and the chemical components of the binder and fine aggregate will be described. FIG. 5 is a diagram showing the results of multiple regression analysis, (A) is a table showing multiple regression equations, (B) is a table showing accuracy, and (C) is a table showing analysis of variance.

Regarding the value of mass reduction rate on the 32nd day of the above-mentioned sulfuric acid resistance test, SiO ₂ and CaO as the main components among the chemical components constituting the binder and fine aggregate are selected as explanatory variables (independent variables). Multiple regression analysis. The significance level is 0.05, and it can be judged that the analysis accuracy is good.

As a result of the analysis, since the coefficient of determination in FIG. 5 (C) is located sufficiently close to 1 at 0.9662, these four components (SiO ₂ in the binder, CaO in the binding material, SiO ₂ in fine aggregate, fine It is thought that CaO in the aggregate contributes to sulfuric acid resistance.

The partial regression coefficient in FIG. 5 (A) means the influence of explanatory variables on sulfuric acid resistance. A positive value means a decrease in sulfuric acid resistance, and a negative value means an improvement in sulfuric acid resistance. Accordingly, SiO ₂ in the binder showing a positive value and CaO in the fine aggregate improve the sulfuric acid resistance, and CaO in the binder showing a negative value and SiO ₂ in the fine aggregate. It can be seen that reduces sulfuric acid resistance. Further, the standard partial regression coefficient in FIG. 5A means the relative influence of explanatory variables on sulfuric acid resistance, and a negative value having a large absolute value means improving sulfuric acid resistance. . Therefore, it can be seen that CaO in the fine aggregate showing a negative value having a large absolute value improves the sulfuric acid resistance.

This multiple regression analysis result is in agreement with the above-mentioned sulfuric acid resistance test result. That is, specimens using PFBC ash (n20050, b20050, etc.) are superior in sulfuric acid resistance to specimens using ordinary cement (NCn, NCb). This is probably because the content of SiO ₂ is large and the content of CaO is small. In addition, the specimen (b20050) using blast furnace slag granulated sand is superior in sulfuric acid resistance to the specimen (n20050) using mixed sand. This is probably due to the high content of.

It is a figure which shows the relationship between the binder water ratio of the mortar composition of an Example, and compressive strength. It is a figure which shows the relationship between the binder water ratio of the mortar composition of an Example, and bending strength. It is a figure which shows the sulfuric acid resistance test result of the mortar composition of an Example and a comparative example in which mixed sand was used. It is a figure which shows the sulfuric acid resistance test result of the mortar composition of an Example and a comparative example in which blast furnace slag granulated sand was used. It is a figure which shows a multiple regression analysis result, (A) is a table | surface which shows a multiple regression equation, (B) is a table | surface which shows an accuracy, (C) is a table | surface which shows an analysis of variance.

Claims (10)

A sulfuric acid resistant structure used in an environment where it comes into contact with sulfuric acid , comprising a binder containing fine PFBC ash and blast furnace slag fine powder , fine aggregate, and water, and comprising a cement-free mortar composition A sulfate-resistant structure characterized in that 2. The sulfuric acid resistant structure according to claim 1 , wherein the fine aggregate is sand in which sea sand and mountain sand are mixed at a ratio of 1: 1. 2. The sulfuric acid resistant structure according to claim 1 , wherein the fine aggregate is blast furnace slag granulated sand. The sulfate-resistant structure according to any one of claims 1 to 3 , wherein the mortar composition has a compressive strength of 18 N / mm ² or more at a material age of 28 days, and 1/5 to 1/7 of the compressive strength. A sulfate-resistant structure characterized by having a bending strength of at least a degree. The sulfate-resistant structure according to any one of claims 1 to 4 , wherein the PFBC ash has a dense hardened body structure by acting as an alkali stimulating material. A sulfuric acid resistant repair material applied to a sulfuric acid resistant structure used in an environment in contact with sulfuric acid,
A sulfate-resistant repair material comprising a binder, fine aggregate, and water containing PFBC ash and blast furnace slag fine powder , and a mortar composition containing no cement. The sulfate-resistant repair material according to claim 6 , wherein the fine aggregate is sand in which sea sand and mountain sand are mixed at a ratio of 1: 1. The sulfuric acid-resistant repair material according to claim 6 , wherein the fine aggregate is blast furnace slag granulated sand. The sulfate-resistant repair material according to any one of claims 6 to 8 , wherein the mortar product has a compressive strength of 18 N / mm ² or more at a material age of 28 days, and 1/5 to 1 / of the compressive strength. A sulfate-resistant repair material characterized by having a bending strength of about 7 or more. In sulfuric acid repairing material according to any one of claims 6 to 9, sulfuric acid repairing material, wherein the PFBC ash has a dense cured product tissues by acting as alkali activator material.

Images